ADS1158: ADS1158 DRDY pin not going LOW

Hi Bryan,

Right after i power up the ADC , start pin remains LOW, after that i tie START, RESET, PWDN to 5v, but DRDY still remains HIGH(3v3).

Hi Bryan , 

This is the code that i am using on arduino:

#include<SPI.h>
uint8_t reg1, reg2, reg3, reg4, reg5, reg6, reg7, reg8 ;

void setup (void)

{

Serial.begin(115200); //Starts Serial Communication at Baud Rate 115200

// pinMode(7, OUTPUT);//start//pulse conver is used
pinMode(9, INPUT);//drdy
pinMode(8, OUTPUT);//reset // tied to 5v 
pinMode(6, OUTPUT);//pwdn //tied to 5v
//digitalWrite(7,LOW);
SPI.begin(); //Begins the SPI commnuication

}

void loop(void)

{

for(int i = 0 ; i <6 ; i++)
{
Serial.println(i);

//////////////////////////////////
digitalWrite(SS,LOW);delay(5); //toggle the ss signal to reset the spi interface as per ads1158 datasheet
digitalWrite(SS,HIGH);

digitalWrite(SS,LOW);

delayMicroseconds(1);
SPI.transfer(0x40);
byte config0 = SPI.transfer(0);
Serial.print("config0:");Serial.println(config0,HEX);
digitalWrite(SS,HIGH);
delay(1000);

digitalWrite(SS,LOW);delay(5); //toggle the ss signal to reset the spi interface as per ads1158 datasheet
digitalWrite(SS,HIGH);
digitalWrite(SS,LOW);
delayMicroseconds(1);
SPI.transfer(0x41);
byte conf1 = SPI.transfer(0);
Serial.print("config1:");Serial.println(conf1,HEX);
digitalWrite(SS,HIGH);
delay(1000);

digitalWrite(SS,LOW);delay(5); //toggle the ss signal to reset the spi interface as per ads1158 datasheet
digitalWrite(SS,HIGH);
digitalWrite(SS,LOW);
delayMicroseconds(1);
SPI.transfer(0x42);
byte MUXSCH = SPI.transfer(0);
Serial.print("MUXSCH:");Serial.println(MUXSCH,HEX);
digitalWrite(SS,HIGH);
delay(1000);
//////////////////////////////////////////
digitalWrite(SS,LOW);delay(5); //toggle the ss signal to reset the spi interface as per ads1158 datasheet
digitalWrite(SS,HIGH);
digitalWrite(SS,LOW);
delayMicroseconds(1);
SPI.transfer(0x43);
byte muxdif = SPI.transfer(0);
Serial.print("muxdif:");Serial.println(muxdif,HEX);
digitalWrite(SS,HIGH);
delay(1000);
//////////////////////////////////////////////
digitalWrite(SS,LOW);delay(5); //toggle the ss signal to reset the spi interface as per ads1158 datasheet
digitalWrite(SS,HIGH);
digitalWrite(SS,LOW);
delayMicroseconds(1);
SPI.transfer(0x44);
byte muxsg0 = SPI.transfer(0);
Serial.print("muxsg0:");Serial.println(muxsg0,HEX);
digitalWrite(SS,HIGH);
delay(1000);
//////////////////////////////////////////////
digitalWrite(SS,LOW);delay(5); //toggle the ss signal to reset the spi interface as per ads1158 datasheet
digitalWrite(SS,HIGH);
digitalWrite(SS,LOW);
delayMicroseconds(1);
SPI.transfer(0x64);
SPI.transfer(0x01);
delay(1000);
/////////////////////////////////////////////
digitalWrite(SS,LOW);delay(5); //toggle the ss signal to reset the spi interface as per ads1158 datasheet
digitalWrite(SS,HIGH);
digitalWrite(SS,LOW);
delayMicroseconds(1);
SPI.transfer(0x45);
byte muxsg1 = SPI.transfer(0);
Serial.print("muxsg1:");Serial.println(muxsg1,HEX);
digitalWrite(SS,HIGH);
delay(1000);
/////////////////////////////////////////////
digitalWrite(SS,LOW);delay(5); //toggle the ss signal to reset the spi interface as per ads1158 datasheet
digitalWrite(SS,HIGH);
digitalWrite(SS,LOW);
delayMicroseconds(1);
SPI.transfer(0x65);
SPI.transfer(0x00);
digitalWrite(SS,HIGH);
delay(1000);
/////////////////////////////////////////////////
digitalWrite(SS,LOW);delay(5); //toggle the ss signal to reset the spi interface as per ads1158 datasheet
digitalWrite(SS,HIGH);
digitalWrite(SS,LOW);
delayMicroseconds(1);
SPI.transfer(0x46);
byte sysred = SPI.transfer(0);
Serial.print("sysred:");Serial.println(sysred,HEX);
digitalWrite(SS,HIGH);
delay(1000);
//////////////////////////////////////////////////
digitalWrite(SS,LOW);delay(5); //toggle the ss signal to reset the spi interface as per ads1158 datasheet
digitalWrite(SS,HIGH);
digitalWrite(SS,LOW);
delayMicroseconds(1);
SPI.transfer(0x47);
byte gpioc = SPI.transfer(0);
Serial.print("gpioc:");Serial.println(gpioc,HEX);
digitalWrite(SS,HIGH);
delay(1000);
//////////////////////////////////////////////////
digitalWrite(SS,LOW);delay(5); //toggle the ss signal to reset the spi interface as per ads1158 datasheet
digitalWrite(SS,HIGH);
digitalWrite(SS,LOW);
delayMicroseconds(1);
SPI.transfer(0x48);
byte gpiod = SPI.transfer(0);
Serial.print("gpiod:");Serial.println(gpiod,HEX);
digitalWrite(SS,HIGH);
delay(1000);
/////////////////////////////////////////////////////
digitalWrite(SS,LOW);delay(5); //toggle the ss signal to reset the spi interface as per ads1158 datasheet
digitalWrite(SS,HIGH);
digitalWrite(SS,LOW);
delayMicroseconds(1);
SPI.transfer(0x49);
byte id = SPI.transfer(0);
Serial.print("id:");Serial.println(id,HEX);
digitalWrite(SS,HIGH);
//////////////////////////////////////////////////////////
delay(1000);

while(1)
{ digitalWrite(SS,LOW);delay(5); //toggle the ss signal to reset the spi interface as per ads1158 datasheet
digitalWrite(SS,HIGH);
// digitalWrite(7,HIGH);//start high
delay(100);
//////pulse convert command
digitalWrite(SS,LOW);
// delayMicroseconds(1);
SPI.transfer(0x80);
byte pulse = SPI.transfer(0);/////////////////////
Serial.print("pulse=");
Serial.println(pulse, HEX);
digitalWrite(SS,HIGH);
// SPI.transfer(0x00);
if (digitalRead(9)==LOW)//drdy
{
digitalWrite(SS,LOW);
// delayMicroseconds(1);
SPI.transfer(0x30);
reg1 = SPI.transfer(0x00);
reg2 = SPI.transfer(0x00);
reg3 = SPI.transfer(0x00);
reg4 = SPI.transfer(0x00);
// digitalWrite(2, LOW);
// dataF=reg2*pow(2,16)+reg3*pow(2,8)+reg4;
Serial.print("Stat=");
Serial.println(reg1, HEX);
Serial.print("msb=");
Serial.println(reg2, HEX);
Serial.print("lsb=");
Serial.println(reg3, HEX);
Serial.print("reg4=");
Serial.println(reg4,HEX);
// Serial.print("finalData=");
//Serial.println(dataF, HEX);
// }
digitalWrite(SS,HIGH);
// delay(1000);
}
}}}

The ADC module is powered via J5A jumper with 5v, 3v3, 1v8 voltages. AINCOM is grounded, J6A-4 is grounded, EREFP is 5v, EREFN is 0v,  Sine wave input at AIN0 channel (auto scan mode).

Hi Harsh Gola,

You should be using either 1.8V or 3.3V, I am not sure why you have both connected. Can you send me some pictures of the new hardware configuration? Please provide as much detail as possible

Can you make sure that PWDN, START, and RESET are tied to 3.3V, then power up the ADS1158 EVM daughtercard. You can even disconnect the controller for this test. When the ADC powers up, the DRDY should toggle at the data rate. If DRDY does not toggle, it just stays high, then there are issues with the power supply or the clock.

Let me know what happens, and please send pictures

-Bryan

Hello Bryan,

I thankyou for your continuous support, I have attached some pictures of the board, please check, i have tied RESET, PWDN, UNIPOLAR/POLAR pins to HIGH(5v from arduino, should i tie them to 3v3 instead?), EREFP is tied to 5v EREFN is tied to GND, and START pin is open, since i decided to use Pulse Convert Command(because setting the START pin did not result in activity on DRDY pin). In the above code i am sending 0x80 then checking the DRDY for LOW condition, then sending 0x30 and additional 0x00 0x00 0x00 to capture STAT , MSB , LSB byte. The registers I changed are muxsg0 (set to 0x01), muxsg1(set to 0x00) every other register is set to default.  

hello bryan,

update :- i found the jumper on the ads1158 board , jumper J6 , it had G0 and ST pin shorted(found this on another forum), I have now changed it to short J6-1 and ST, now the DRDY pin is pulsing and it should when it set the START pin high. Now i am changing the arduino code to set START pin high initially, then check DRDY for LOW and send (0x30)(0x00)(0x00)(0x00) to retrieve the channel, i will update asap about the channel data i am receiving.

FLOW:- 

1.set RESET, PWDN, UNIPOLAR, START pin high (5v, should i tie it to 3v3 instead?)

2.set configuration registers

3.read back those registers

4. check DRDY for LOW , then send (0x30). and stay in this state.

Please check if i am taking the right approach.

thankyou.

Thankyou Bryan for your Guidance, I have attached some images of the results i am getting, please check and let me know if you need more detailed images, currently i am using one channel (AIN0) for testing, i want to use 7 channels ultimately(AIN0-AIN6)(Single-ended), the ADC is running on default configuration, i have only overwritten the muxsg0(0x01) and muxsg1(0x00) register to select the in put channels. i am using RESET, PWDN, START, DRDY, CS,MOSI, MISO,SCLK pins in total , adc is powered without the motherboard now, i provided a sine wave as input and result is noisy. in my current code i write muxsg0 and muxsg1 then take start pin from low to high, then start checking drdy for low and then send (0x30000000) to retrieve the channel data. please guide as to how can get the result with less noise.

Thankyou

Hello Bryan,

i am able to read and write registers successfully, i am using this adc to measure data from sensors like, humidity, water pressure, temperature and water flow. i have attached some images , one showing spi communication, other showing the data i am receiving.  you might notice , it is mentioned in the sheet , that the NEW bit represents new Data, so i have separated the data in to two , one where i am collecting New and Old data, named, ads_1158_interface_ 0_channel_n (n= 0,1,2,3,4,5,6), and one where i am collecting only New data and discarding Old data, named, ads_1158_interface_0_channel_n_new.

but i am still getting spikes at uneven instances. The sensors connected currently are, a humidity sensor(channel 1), 2 water pressure sensors(channel 0 and 2), a 5v dc source(channel 3) ,a 2v 100hz sine wave(channel 5).

SPI clock = 8mhz, SPI triggering whenever DRDY goes LOW.   channel 0 to 6 enabled on ADC , others are set to 0 (off), autoscan mode, channel data read command. 

all register are at default value, except muxsg1 = 0x00.

Hello Bryan,

ads_1158_interface_0_channel_n (where n is channel no.) represent the channel no. , e.g. ads_1158_interface_0_channel_0 shows AIN0 data, and ads_1158_interface_0_channel_0_new also shows AIN0 data except that it discards old data every time based on status byte's NEW bit, e.g. old data on AIN0 channel is shown as 0x08(StatusByte) MsbByte LsbByte and new data as, 0x88(stat byte) Msb Lsb.

I am collecting all the data on the DOUT buffer of the SPI module then checking the STAT byte to get the channel info, and then plot them separately.

i am currently using the ads1158 module without the motherboard , i have connected j6-4 ground to fpga and connected AINCOM to GND pin on the ads1158 module. i have also connected the ground of the sensors to the ads1158 module and fpga both.

Hi Harsh Gola,

Have you tried checking the stability and voltage at your power supplies? Do they droop at all when you are sampling?

Have you tried using an external reference voltage from a precision source to see if the noise decreases?

For now, I would also only input a known DC voltage to test your circuit and diagnose the noise. There are too many variables when you start trying to measure sensors, etc.

-Bryan

Hello Bryan,

i am supplying 5v DC to the ADC from a dedicated Power Supply Unit, although it dops to 4.9 or even 4.7 , it does not drop to or go near 0v. 

For external reference i have set S1 and S2 switches to AVDD and GND respectively.

i am also supplying a steady 5v DC signal to just one channel but, i am still getting dips whose values even go as low as 0(on the analyzer window).

but whenever i run the ADCPro software to double check if there is noise in the signal, it runs just perfectly.

Registers configuration:-

Config0 = 0x0a

config1 = 0x83

muxsch = 0x00

muxsg0 = 0x01

muxsg1 = 0x00

i am fetching channel data whenever DRDY signal goes low.

SPI clock  8 MHZ.

Hi Harsh Gola,

If AVDD is dropping to 4.7V, this is below the recommended operating conditions of the ADC (AVDD must be AVSS+4.75V, and I assume you are measuring AVDD with respect to AVSS). This could cause a wide range of issues within the ADC, since the ADS1158 is designed to operate at effectively 5V AVDD.

I would ensure that your power supply is very stable and does not droop. There is a chance this might not resolve your immediate issues, but it very likely could cause future challenges

What is your IO voltage on the board? Is that supply drooping as well?

-Bryan